“I was very respectful and I went there to deliver a letter,” she continued. “Nobody was turned away, nobody was disrespectful and it was a wonderful experience. It was a nice experience and nobody was mean to me at all, I was quite surprised.”

Samantha’s characterization of her demeanor at the Palace is in line with what a source told ET earlier this week, calling the writer “upbeat and cheery.”

“[Samantha] seemed delighted to see souvenir stands close by selling royal collectibles and purchased two commemorative Meghan and Harry wedding mugs and cardboard face masks," the source added.

Samantha remained mum about the exact contents of the letter, but said, “I think I accomplished my goal and we’ll just have to wait and see how it was received.”

“I wanted to express some sentiments and set some records straight,” Samantha shared to DailyMailTV. “I can’t give the details of that but I really wanted the world and really my sister and the British royal family to know what happened and know the truth about a lot of things.”

As for a direct plea to her 37-year-old half-sister, Samantha had a lot to say.

“Let’s just cut through all the crap, you’re a woman, life is short. I believe you have it in your heart to do the right thing here,” Samantha said. “You know Dad loves you, you know he’s been there for you more than anyone, so don’t let this public monster and misperception that he’s like a sperm donor dad trying to be involved all of a sudden.”

Samantha continued to stick up for her father, whom, she claims, Meghan lived with “for much of her life” and whose treatment by Meghan and the royal family has been, she says, “all grossly unfair.”

“You know that’s not true and so to let that happen, come on Meg, have a heart, I know you’re a woman, I know you have a heart in there,” Samantha said. “God, the Grinch grew a heart, albeit at the last minute. I’m not comparing you to the Grinch but I will say I know you have it in you to make this right.”

Though she’s not taking anything off the table, Samantha knows that there’s one thing she would not do to get to her sister -- contact the queen.

“Addressing her is not appropriate. I know people have done that before – my brother – but she’s 93, 94 years old, it’s not her issue,” she said. “It’s very disrespectful to address the queen, so no, I’m not going that route. I know the public would love me to or say that’s my next move but I’m not tacky.”

As much as she’d like Meghan “to do the right thing,” Samantha has placed “the ball in my sister’s court.”

“It’s a real family and life is very short so I just hope, for her sake as well, that Meg doesn’t let this go,” she said. “I was concerned about my father passing away without resolve here because that would be awful for everybody and I really doubt she could live with that. She needs to do the right thing.”

According to a source, though, it’s unlikely that Meghan will reach out to her family.

"The Palace doesn't want to dignify any of it because it just adds fuel to the fire. Samantha revels in the attention. Meghan is not corresponding with her sister or father [Thomas Markle]," a source told ET.

"Meghan loves her new role," the source continued. "She takes it very seriously and wants to make a difference. She's mindful that she's representing the queen and the royal family and doesn't want to put a foot wrong."

Watch the video below for more on how Meghan is handling Samantha’s drop-in visit: